Validation of the Japanese version of the CDC HRQOL‐4 in workers

BACKGROUND: We set out to investigate the reliability and validity of the Japanese version of the CDC core healthy day measures assessing health‐related quality of life (CDC HRQOL‐4) in Japanese workers. METHODS: This cross‐sectional study was conducted among 1360 Japanese workers of one Japanese company located in Kyushu. Cronbach's alpha was calculated to evaluate the internal consistency of CDC HRQOL‐4 items. The concurrent validity was tested by assessing whether the CDC HRQOL‐4 items correlated well with the corresponding domains of the SF‐8 and the overall WFun score. The construct validity was tested by assessing the ability of the CDC HRQOL‐4 to discriminate groups with and without any current disease, pain, mental problem, and sleeping disorder. RESULTS: Cronbach's alpha for three of the four CDC HRQOL‐4 items was 0.80, which is greater than the minimal standard (0.70) recommended for internal consistency reliability. Correlation coefficients ranging from 0.25 to 0.67 were obtained between CDC HRQOL‐4 items and the SF‐8 domains and WFun score. Workers with any current disease, mental problem, pain or sleeping disorder reported higher numbers of unhealthy days, and a higher odd of poor health than those without such problems. Japanese version of the CDC HRQOL‐4 shows a good concurrent validity with the SF‐8 and the WFun tool and good construct validity among Japanese workers in the current study. CONCLUSIONS: Japanese version of the CDC HRQOL‐4 is a reliable and valid instrument that may be used to assess overall health and physically and mentally unhealthy days in Japanese workers.